1. Technical Field
The present invention relates to a package substrate for an optical element and a method of manufacturing the same.
2. Description of the Related Art
Recently, light emitting diodes (LEDs) are continuously increasing in demand and are gradually receiving attention from the general illumination market, because they are environmentally friendly and achieve energy saving effects including lower power consumption, higher performance, longer operating lifespan, etc., compared to conventional optical elements such as incandescent or fluorescent lamps.
Furthermore, because such an LED may exhibit higher image quality compared to a cold cathode fluorescent lamp conventionally used as a light source of a liquid crystal display, package substrates for an optical element using the LED as a backlight unit are being introduced one after another.
The package substrate for an optical element is a substrate on which electrical components including integrated circuits, resistors or switches are soldered, and is mounted to circuits used in computers or a variety of displays.
Upon fabrication of the package substrate for an optical element, a fluorescent resin material is typically applied in order to emit white light. As such, in the case where the size or thickness of the optical element has increased, there may occur a problem in which the shape of the applied fluorescent resin material is not maintained in the form of a dome. With the goal of solving this problem, a conventional technique discloses a package substrate for an optical element in which a thickness difference is created using metal at a portion of the package substrate on which an optical element will be mounted, but the thickness difference causes other problems.
FIG. 1 is a cross-sectional view showing a package substrate for an optical element according to a conventional technique. With reference to this drawing, the problems of the conventional technique are described below.
As shown in FIG. 1, the dome shape of a fluorescent resin material 2 may be maintained by a thickness difference 1, but a circuit layer cannot be formed around an optical element 3 and thus a via 4 must be formed at the position of a package substrate where the optical element 3 will be mounted in order to form an electrical connection.
Thus, a plugging process for filling the empty space of the via 4 with epoxy should be additionally performed, undesirably complicating the manufacturing process. When the via 4 is filled with epoxy, voids are formed, undesirably lowering reliability of the via 4. Furthermore, heat dissipation properties of the substrate 5 for heat occurring from the optical element 3 are deteriorated due to epoxy.
Moreover, there are the problems of the optical element 3 being inclined by the via 4 upon mounting of the optical element 3 or that of a die attach adhesive for adhering the optical element 3 infiltrating the via 4 and undesirably leaking out of the opposite surface of the substrate 5.